Other countries including France and Belgium have already been hit hard by the disease but Denmark has been the worst affected - losing 90% of its ash population.

There are fears the infection could have the same impact in Britain as the infamous Dutch Elm epidemic of the 1970s, which wiped out most of the country's elm trees.

There are an estimated 80 million ash trees in Britain - one-third of the entire tree population.

Several National Trust sites, including Ashridge in Hertfordshire, have put up signs as an extra precaution to prevent the disease spreading.

Ashridge Estate , a site popular with walkers that has been used in several films including Harry Potter And The Goblet Of Fire, has hundreds of ash trees in its 5,000 acres of woodland.

Estate manager Graeme Cannon told Sky News: "It's potentially very dangerous. Ashridge is here because ash trees feature very prominently in its background and they have done for hundreds, if not thousands, of years.

''With ash dieback in the country we'll end up in a situation where we will be losing a lot of our trees and they are an important feature of the British landscape and woodland.

"So far we have not had any confirmed cases in Ashridge but if we do then the impact would be catastrophic.''

Infected saplings are being burned but visitors to woods are also being asked to do their bit by keeping to marked paths to help reduce the spread of infected leaves.

They are also being advised to clean footwear and bike and car tyres of mud and earth when they get home.

Although the Government claims it has acted as swiftly as it could, there has been some criticism that the response has not been quick enough.